More than 1,000 houses in Rohingya villages have been razed in northwestern Myanmar, according to analysis of satellite images from Human Rights Watch released Monday that fly in the face of government denials.

Troops have poured into a strip of land along the Bangladesh border, an area which is largely home to the stateless Muslim Rohingya minority, since a series of coordinated and deadly attacks on police border posts last month.

Up to 30,000 people have been displaced by the ensuing violence, according to the UN, half of them over a two-day period when dozens died after the military brought in helicopter gunships.

Security forces have killed almost 70 people and arrested more than 400 since the lockdown began six weeks ago, according to state media reports, but activists say the number could be far higher.

Hundreds of Rohingya, who have long been persecuted by the state, have tried to flee the violence to neighbouring Bangladesh.